1. Field of the Invention
The invention relates to methods for recovery and separation of high explosive from aged munitions and more particularly to a method for reclaiming a high explosive from warhead by striping down at a temperature below the melting point in supercritical fluid and inducing a sonicating process simultaneously.
2. Description of Related Art
How to effectively remove obsolete and aged munitions and explosive inventories from the active arsenal in a safe manner is of great concern. Typically, demilitarization programs focused on disposal or destruction. Recently, there have been efforts to develop recycling and/or reclamation processes that permit explosives and higher valued constituents of munitions systems to be recovered and re-used in military applications due to environmental protection.
Typical methods for demilitarization separation techniques include melting out, steaming/water washout and solvent washout of the high explosive from the projectile casing. Typical methods for melting out and steaming/water washout are operation at a temperature above the melt point and take high explosive phase transition from solid to liquid. Solvent washout is solution high explosive to be separated. These three methods are disadvantageous for being time consuming, inappropriate for mass reclamation of explosive, generating too much polluted waste water which is required to treat in prohibitively high cost, and being low efficiency.
U.S. Pat. No. 5,953,679 to Morris discloses a method for the extraction of TNT from a high explosive comprising contacting the high explosive with a supercritical fluid at a temperature above the melting temperature (e.g., 85 degrees Celsius) of TNT and at a pressure (e.g., 37.4 MPa) sufficient to extract the TNT.
This patent is part of extraction method. In detail, specific substance of the mixture moves from one solvent to another solvent due to different solubilities of different solvents. In example 1, solubilities of TNT and RDX in a supercritical carbon dioxide solvent are illustrated. In examples 2 and 3, how to extract TNT from explosive B is illustrated. In example 4, explosive is first molten out of a shell by subjecting the shell to carbon dioxide in a temperature of 85 degrees Celsius which is higher than the melting temperature of 81 degrees Celsius of the explosive. Next, an extraction is performed for increasing efficiency. In these examples, melting TNT out of a shell by subjecting the shell to carbon dioxide in a temperature higher than the melting point of TNT is a technique within the ordinary skilled artisan in the art and is deemed obvious. Thus, it is very possible that unexpected explosions may occur during the melting-out vessel. This is very dangerous.
Further, in claim 1 of the patent melting TNT out of a shell by subjecting the shell to carbon dioxide in a temperature higher than the melting point of TNT. TNT will melt out of any contained enclosure when subjecting to an environment in a temperature higher than the melting point of TNT. This is within the ordinary skilled artisan in the art and is deemed obvious. Melting point means the temperature at which the solid and liquid phases of a substance are in equilibrium. Thus, it is normal when a substance is molten when it is subjected to an environment having a temperature higher than its melting point. But, special attention should be paid when a substance is molten in a temperature lower than its melting point. In short, the patent is characterized in that the molten TNT is extracted out of a shell by utilizing TNT having a solubility greater than other explosives when subjecting to a supercritical carbon dioxide environment.
It is also known that many explosive components have a very low solubility in carbon dioxide based supercritical fluid. Further, TNT has a very low solubility in carbon dioxide based supercritical fluid. Thus, a great volume of carbon dioxide based supercritical fluid is required for reclaiming TNT from the high explosive. This in turn adversely increases the cost. For example U.S. Pat. No. 5,953,679 to Morris discloses solubility of TNT in supercritical carbon dioxide gas of temperature 65 degrees Celsius and pressure 27.6 MPa is 16 mg/mL. 412.5 liter of supercritical carbon dioxide liquid is used to extract 6,600 gram of TNT from a warhead of a 155 mm gun-howitzer in supercritical carbon dioxide gas of temperature 65 degrees Celsius and pressure 27.6 MPa. The extraction vessel has a capacity of 415 liter and is high of the manufacturing cost. Alternatively, it will take 190 days in a flow rate of 1.5 ml/minute to extract 6,600 gram of TNT from a warhead of a 155 mm gun-howitzer in supercritical carbon dioxide gas of temperature 65 degrees Celsius and pressure 27.6 MPa.
Notwithstanding the prior art, the invention is neither taught nor rendered obvious thereby.